1. Field of Invention
This invention relates to indicators, specifically to one which tells if mail has been deposited in a mailbox at a remote location.
2. Description of Prior Art
Heretofore, mail delivery indicators used mechanical switches and mechanisms to indicate the presence of mail in the box. Others, such as the device in U.S. Pat. No. 4,868,543 to Binkley (1989) required battery maintenance, used valuable radio spectrum, and used complex circuitry. Mailbox in U.S. Pat. No. 4,499,372 to Nakano (1985) employed complex electronic circuitry as above and used multiple emitter/detector pairs. Until now, mail delivery indicators known suffer from a number of disadvantages:
(a) Their design requires the periodic replacement of batteries in the mailbox.
(b) Complex electronic circuitry is required.
(c) Multiple emitter/detector pairs or complex sensor signal paths are used.
(d) Wired versions require more than a single pair of wires.
(e) Radio transmissions from the remote mailbox result in reduced privacy.
(f) Valuable radio spectrum is used for radio transmissions from the remote mailbox.